Editor's note:This is part one of a two-day series examining the Lara Plamann murder investigation.

On a crisp autumn morning in 2007, Lara Plamann's body was discovered in a pole barn behind the home she shared with her romantic partner of nine years. The 30-year-old Greenville woman had been reported missing 13 hours earlier.

Plamann's body was slouched on a metal chair; she had been shot, twice. No gun was in sight.

Yet, Outagamie County Sheriff's Sgt. Mike Jenks, one of the first deputies to view the body that day, suspected suicide.

"Sgt. Jenks and other investigators on the case were of the theory that Lara may have shot herself and someone may have removed the gun in an effort to conceal the suicide for some reason," Jenks wrote in his report, which was obtained by the Gannett Wisconsin Media Investigative Team.

Twice that day, Jenks interviewed 48-year-old Dianna Siveny, Plamann's partner. Jenks was trying to piece together what happened to Plamann between Oct. 17, when she went missing, and Oct. 18, when her body was found.

Lara Plamann was 30 years old when she was murdered in a pole barn on her property in Greenville. Nobody has been convicted in her Oct. 17, 2007 killing.(Photo: photo provided to The Post-Crescent)

Jenks asked Siveny if she found a suicide note. "I was worried that maybe you'd found her and had picked up the gun and now you're distraught and you're not sure what to do ..." Jenks told Siveny in the videotaped interview.

That's how the murder investigation began. Eventually, it unraveled to the point where Plamann's family now holds little hope that Lara's killer will ever be brought to justice.

"As a prosecutor, I can never say on a homicide that we've closed the door to ever filing on a cold case or refiling in any case," Outagamie County District Attorney Carrie Schneider said this week. "You can never predict or know what new information is gathered that changes an investigation."

In 2013, Outagamie County officials charged three women they suspected of hatching a murder-for-hire plot: Dianna Siveny, her daughter Kandi Siveny of Minnesota and Rosie O. Campbell, also of Minnesota. In assembling the charges, investigators made roughly 40 trips to Minnesota, trying to prove their theory.

Back then, law enforcement officials were hopeful the murder had finally been solved. But their case only degenerated from there.

“These investigators for Outagamie County did a completely incompetent job.”

Gregory Gilbertson, expert on law enforcement and police standards and practices

Ultimately, the prosecutor dismissed the homicide charges before any of the three co-defendants stood trial.

"The tragedy of this case is that a murderer remains at large and will likely never be charged," Daniel Kaminsky, the defense lawyer for Dianna Siveny, said in a statement he issued after the charge was dismissed earlier this year. Kaminsky previously served as Fond du Lac County's District Attorney. "The failure to properly investigate this case has left the victim's family and her partner without justice."

Since July, the Gannett Wisconsin Media I-Team has reviewed hundreds of pages of investigative police reports, court transcripts and dozens of recorded interviews from the case. The documents and interviews help shed light on the sheriff's office's missteps and missed opportunities during the investigation.

Officials investigate the area outside the Greenville home of Lara Plamann, 30, whose body was discovered in a storage shed on the property on Oct. 18, 2007.(Photo: File/Post-Crescent Media)

Several days after Lara Plamann's body was found in a pole barn in rural Appleton, Andrea Shay of Appleton is questioned regarding an eyewitness report of a shoving incident near the barn on the day of the murder.(Photo: Outagamie County Sheriff's Office)

Dianna Siveny, then 48, is interviewed at the Outagamie County Sheriff's Office on Oct. 18, 2007, several hours after the body of her partner, Lara Plamann, 30, was found in a barn on their property.(Photo: Outagamie County Sheriff's Office)

Lt. Christopher Proietti interviews Rosie Campbell, of Minnesota, in 2009 about her recollection of supposedly seeing a handgun in the car of her friend Kandi Siveny.(Photo: Outagamie County Sheriff's Office)

Dianna Siveny and her attorney, Len Kachinsky, in Judge Mark McGinnis' courtroom during a preliminary hearing on April 29, 2013 at the Outagamie County Justice Center in Appleton.(Photo: File/Post-Crescent Media)

Photos of Lara Plamann hang on the wall of her parent's wall on October 12, 2015 in Grand Chute. Oct. 18, 2015 marks the eight-year anniversary of the discovery of Lara's body. She had been shot to death.(Photo: Wm.Glasheen/Post-Crescent Media)

Mary Jo Plamann visits her daughter's grave at St. Joseph Cemetery on Oct. 12, 2015 in Appleton. Oct. 18, 2015 marks the eight-year anniversary of the discovery of Lara's body. She had been shot to death.(Photo: Wm.Glasheen/Post-Crescent Media)

Lara Plamann's grave at St. Joseph Cemetery on Oct. 12, 2015 in Appleton. Oct. 18, 2015 marks the eight-year anniversary of the discovery of Lara's body. She had been shot to death.(Photo: Wm.Glasheen/Post-Crescent Media)

Outagamie County Judge Nancy Krueger sharply criticized the performance of the Outagamie County Sheriff's Office in the Lara Plamann murder case.(Photo: File/Post-Crescent Media)

The Gannett Wisconsin Media I-Team's review of the documents also found that authorities didn't work with a sense of urgency and their work was not thorough.

Among the numerous pitfalls:

The entire first day of the case was investigated as a probable suicide.

Authorities overlooked or ignored obvious local murder suspects.

Investigators relied on help from a local psychic who predicted an elaborate murder for hire conspiracy.

Two women, both drug addicts from Minnesota, were arrested for killing Plamann even though no solid evidence put them in Wisconsin around the time of the killing.

"These investigators for Outagamie County did a completely incompetent job," said Gregory Gilbertson, a nationally recognized expert on law enforcement and police standards and practices from Olympia, Washington. "These cops, for whatever reason, totally mishandled this case. It's fatally flawed from the beginning. I believe it could have been solved during the initial stages of the investigation. I absolutely do."

Plamann, Siveny met in 1998

Plamann grew up on a farm near Appleton. She was active in the Outagamie County 4-H, police reports show.

Dianna Siveny was 48 years old when her domestic partner of nine years, Lara Plamann, was slain on their property in 2007.(Photo: Photo courtesy of law enforcement)

In 1998, Plamann was finishing her business degree at St. Norbert College in De Pere. That year, she crossed paths in an online chat room with Dianna Siveny, who was nearly 20 years older, and lived 3,500 miles away in Alaska. Siveny moved to Wisconsin and they became domestic partners. They later bought an acreage along State 96 in Greenville. They made about $70,000 annually selling dog agility equipment from their home-based business, interview statements reflect.

Siveny and Plamann had an "open relationship," reports state, allowing each partner to see other people. Siveny had a friendship with an Oshkosh woman, but it was not intimate. Since early 2006, Plamann had been in a sexual relationship with an Appleton woman, Andrea Shay, police reports show. They met while working at Oshkosh Truck. They broke off their romance about two weeks prior to Plamann's murder, but agreed to remain friends.

Shortly before 7 p.m. on Oct. 17, 2007, Plamann was set to drive to the Appleton woman's home to watch a movie, according to reports. But an hour passed and the woman began to wonder why Plamann didn't show up. She called Plamann's phone, but it went to voicemail. The Appleton woman and Siveny talked on the phone at least twice that night, discussing how to proceed.

Siveny reported Plamann missing at roughly 10 p.m. After his squad car rolled up to Siveny's house in Greenville, Outagamie County Sheriff's Sgt. Pete Gervais noticed Plamann' s new Pontiac Grand Prix parked in her driveway. Plamann's wallet, license and credit cards were all inside the unlocked car, the sergeant noted in his reports.

But Plamann was nowhere to be found.

CLOSE

Dianna Siveny calls police dispatchers around 10 p.m. on Oct. 17, 2007 alerting them that her romantic partner, Lara Plamann, 30, failed to show up at the home of an Appleton woman for a regularly scheduled date night.

"When I asked Dianna if Lara had left with any personal belongings, she said 'no.' When I asked if they had a fight, she said 'no,'" Gervais wrote.

It was dark and raining at the time, and Plamann was missing under suspicious circumstances. Her cellphone was found inside the home. Still, Gervais, a veteran sheriff's deputy, did not summon back-up help, the I-Team learned. He also did not walk the property or check the large outbuildings down the hill from the couple's home. He also didn't contact the Appleton woman or Plamann's parents.

An Outagamie County Sheriff's road deputy responded to a missing person's call in Greenville on Oct. 17, 2007, but decided not to search the property for Lara Plamann even though her car, wallet and keys were all found in her driveway.(Photo: Outagamie County Sheriff's Office)

Instead, Siveny was urged to call the sheriff's office back the next morning, if her partner did not return home, police reports indicate. The deputy didn't check the unlocked pole barn before he drove away, the I-Team learned. Had he done so, Plamann's body would have been found many hours earlier.

The deputy's lapse gave Plamann's killer plenty of time to destroy and conceal potential evidence, including the handgun, which was never found, the I-Team learned.

"This deputy should have walked every inch of the property that night," Gilbertson said. "It just makes no sense to me why he didn't. That deputy is responding to a missing person's call, and here's the missing person's car."

The next morning, Siveny alerted the sheriff's office that Plamann had not returned. But she persuaded deputies to wait a couple of hours before searching her property because she had errands to run, reports show.

About 8 a.m., Siveny drove to Plamann's parents to do the morning chores on their Grand Chute farm. Plamann's mother, Mary Jo, became furious after learning her daughter was missing and Siveny was not looking for her, reports state.

CLOSE

Dianna Siveny calls the Outagamie County Sheriff’s Office the morning of Oct. 18, 2007, notifying dispatchers that her romantic partner, Lara Plamann, had not returned to their home last night.

By late morning, a team of sheriff's investigators found Plamann's body in the large shed about 100 feet down the hill from the house she owned with Siveny. Inexplicably, sheriff's detectives didn't recognize they had a killer on the loose even though the gun was gone, the I-Team discovered.

Also, even though the homicide victim had been involved in a three-way sexual relationship with Siveny and Shay, the sheriff's office did not immediately treat either woman as a prime suspect, documents reflect. That night, Siveny's interview at the sheriff's office was fueled by speculation of suicide.

"There's something we're missing," Jenks told Siveny. "I'm not sure where to look. We now know it was a gunshot but we don't know if it was self-inflicted or it was inflicted by another person."

CLOSE

Dianna Siveny, then 48, is interviewed at the Outagamie County Sheriff's Office on Oct. 18, 2007, several hours after the body of her partner, Lara Plamann, 30, was found in a barn on their property.

The sheriff's office let several more days pass before they took a formal statement from the Appleton woman surrounding her activities on the night of Plamann's murder. Shay maintained she drove to the Grand Chute Barnes & Noble after Plamann didn't show up for their movie date. However, Jenks and colleague Sgt. Chris Hammen didn't corroborate her statement after learning the retail store lacked video surveillance cameras, reports showed.

Solid leads go undeveloped

After news of the Greenville murder appeared in The Post-Crescent, a Green Bay woman alerted Outagamie County authorities to a creepy online message posted by a man. "While (he) had always seemed strange, now he was making a posting on one of the sites about a girl being murdered only 3/4 of a mile from his house," police reports stated. The man, then 59, posted on a website that "she got what she deserved. She's pretty poison."

Jenks and Hammen noted in their reports they remembered the man because he was suspected of sending photos of his genitalia to women years earlier. When the detectives went to the man's house, they noticed an extensive collection of firearms displayed in his living room.

CLOSE

Several days after Lara Plamann's body was found in a pole barn in Greenville, Andrea Shay of Appleton is questioned regarding an eyewitness report of a shoving incident near the barn on the day of the murder.

"He admitted that he had made online postings about the Plamann murder which happened near his house," police reports noted. "He told the investigators that the photo of the murder victim in The Post-Crescent resembled a former bartender at a Greenville bar."

Hammen and Jenks thanked the man for his time and did not consider him a possible suspect. They also did not inspect his collection of firearms as the possible murder weapon, the I-Team determined. "It became apparent to the investigators that (the resident) was dealing with some mental health issues and had mistaken Lara Plamann's picture for someone else," their reports stated.

A woman in Dale told authorities she saw a pushing match on the day of Plamann's murder as she drove past the rural property around 3:30 p.m. Days later, Jenks informed the Appleton woman who had a prior relationship with Plamann that an eyewitness saw an argument outside the pole barn where the murder occurred.

"One of them certainly looks like Lara," he revealed during the videotaped interview at the sheriff's office, "and the other person sounds like you from the description."

Shay, who worked at a domestic violence shelter in Oshkosh, recalled she did not work on the day of the murder, but maintained she was probably home. "I wasn't over there," she responded. "I can't imagine Lara being outdoors in a physical fight with anyone."

Jenks assured the Appleton woman that the witness' description did not match Siveny, who styled her light blonde hair in a mullet. "It wasn't Di, that's obvious to me because you can't mistake Di's hair," Jenks said. "You can see that hair from a mile away."

Over time, the eyewitness' tip became insignificant. Investigators also did not pursue the Appleton woman as a potential suspect. In 2014, Hammen testified that his agency had not subpoenaed any cell tower records for her cellular phone. She later moved to Florida.

Police overlook gun leads from Alaska

After the slaying, the Wisconsin Crime Laboratory in Madison determined that an AMT .380 Back Up stainless steel pistol was the likely murder weapon. That semi-automatic gun had not been made since the 1990s.

"The most likely ammunition used is Frontier 380Auto cartridges manufactured by Hornady," the Nov. 6, 2007, report stated. This likely brand of bullets had not been made since 1994, police reports state. Hornady was based in Grand Island, Neb. During an interview, Siveny told Jenks and Hammen she and Plamann never had any guns. She insisted she never owned a gun in her life.

"I don't kill things," she told Jenks.

This copper bullet was used to kill Lara Plamann in the pole barn on her property in October 2007.(Photo: Outagamie County Sheriff's Office)

Originally from Minnesota, Dianna (Fuchs) Siveny had also lived in Nebraska and Alaska, interviews revealed. Her husband was stationed at the Air Force base near Omaha when he discovered his wife involved in a rendezvous with a college girl, investigative reports stated. The married couple separated in 1987 and their divorce became official in 1991.

From 1988 until 1998, Siveny was in Alaska where she had a relationship with a woman and they ran a painting business, reports state. During a phone interview, the woman told investigators that Siveny once pulled out a gun and fired a shot out the window of their vehicle as they drove through Wasilla around 1995.

Additional reports reflect Siveny displayed a shiny chrome-plated pistol around 1996 near a rest stop by North Pole, Alaska.

Investigative records do not reflect that Outagamie County detectives traveled to Alaska to pursue potential leads regarding firearms or to conduct face to face interviews with people Siveny had known. After about six weeks, the murder began to go cold. Not much was done during December 2007 and part of January 2008 because Jenks was away on family medical leave, reports show.

By late February 2008, Jenks enlisted a friend of Plamann's mother to secretly record her phone calls with Siveny. They hoped to catch Siveny on tape confessing to murder. That never happened.

As the unsolved murder case dragged on, Siveny went on the offensive. By May 2008, she sued the sheriff's office to give her back Plamann's impounded Grand Prix and Plamann's cellphone as assets, reports reflect. Later that month, Plamann's mother told Jenks that her sister-in-law was meeting with a local psychic for insight into the murder. A spelling board was being used to communicate with the victim's spirit and to ask her questions, Jenks' investigative reports stated.

Dianna Siveny is interviewed by officers during the Lara Plamann murder investigation.(Photo: Outagamie County Sheriff's Office)

By late June, Jenks went to Menasha to meet with the psychic, Laurie K. Nelson, in the presence of a few extended relatives of Lara Plamann.

Dianna Siveny was not the person who killed Plamann, the psychic revealed. "I believe Dianna stayed away from the whole thing. She paid somebody to do this," Nelson told Jenks. The name of Dianna's grown daughter, Kandi, was brought up during the psychic encounter as someone who "might have more information."

The psychic suggested the gun might be hidden in a chicken coop belonging to Plamann's relatives. The next afternoon, Jenks and Hammen searched the coop, but the gun was not there.

A week later, Outagamie County learned Dianna's daughter Kandi was arrested for dealing methamphetamine in the Twin Cities.

In the coming years, Hammen and Sgt. Jeff Dietzen theorized that Plamann was brutally shot by out-of-state conspirators in a murder-for-hire scheme. They had the support of long-time Sheriff Brad Gehring to take numerous trips back and forth to Minnesota to try to prove their new theory.

Despite the best of intentions, their efforts to infiltrate the Twin Cities' underworld of street hustlers, meth addicts, crack cocaine users and prison convicts to prove their flawed theory failed to result in the conviction of Plamann's killer.

John Ferak is an investigative reporter for Gannett Wisconsin Media. He can be reached at jferak@gannett.com on Twitter @johnferak

Editor's note:This is part one of a two-day series examining the Lara Plamann murder investigation. See Part II.